The 51-48 vote to table the amendment to a transportation bill fell largely on party lines. Just one Republican -- retiring Sen. Olympia Snowe of Maine -- voted with Democrats against the Blunt amendment.

Three Democrats -- Sens. Bob Casey of Pennsylvania, Joe Manchin of West Virginia and Ben Nelson of Nebraska -- voted with Republicans to support the amendment. Nelson is also retiring.

Sen. Mark Kirk, R-Ill., who is recovering from a stroke, did not vote.

Blunt's amendment would have exempted insurers from having to cover contraception if it violates an employer's religious beliefs.

Republicans cast it as a First Amendment debate that protects religious freedom. The Obama administration's ruling initially would have required faith-based organizations to cover contraception even if it violated the tenets of their faith.

The administration walked back their initial ruling, instead placing a requirement on insurers and not employers to cover contraceptive costs, but Republicans contend that it does not go far enough to protect religious freedoms.

"This isn't a compromise, it's another government takeover. Only this time it isn't the banks or the car companies, it's religion," said Senate Minority Leader Mitch McConnell, R-Ky.

The debate has been a politically perilous, if unavoidable one, for the GOP. While there is considerable support among the Republican base opposing the administration's ruling, the ruling is more popular with swing and independent voters — particularly women — who will play a decisive role in elections in November.

In the Senate debate, Democrats made a unified appeal for women's access to health care and cast the GOP as out of touch with the electorate. A Feb. 8-13 CBS/New York Times poll showed 61% of Americans in favor of the administration's mandate, with 31% in opposition.

"If the senate had 83 women and 17 men instead of 83 men and 17 women, my strong guess is a bill like this would never make it to the floor," said Sen. Bernie Sanders, I-Vt.

Sen. John Kerry, D-Mass., a Catholic who represents a heavily Catholic populated state, argued that the Blunt amendment was itself an infringement on First Amendment rights "The Blunt amendment is in fact an assault on that protection because it imposes one view on a whole bunch of people who don't share that view," he said.

The U.S. House has no immediate plans to vote on similar legislation, but there is broad support within the GOP for Blunt's amendment so a vote is likely. If so, it would be about getting lawmakers on the record on the issue as the election year heats up.

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About Catalina Camia

Catalina Camia leads the OnPolitics online community and has been at USA TODAY since 2005. She has been a reporter or editor covering politics and Congress for two decades, including stints at The Dallas Morning News and Congressional Quarterly. Follow her at @USATOnPolitics.